Carl von Clausewitz’s Moral Science of Warfare

Part of a Series on the Philosophy of History

Nick Nielsen
16 min readJun 2, 2024

Saturday 01 June 2024 is the 244th anniversary of the birth of Carl von Clausewitz (01 June 1780 to 16 November 1831), who was born on this date in Burg bei Magdeburg in 1780. (Wikipedia says that Clausewitz was born on the first of July, rather than June, but it’s possible to find pictures of Clausewitz’s grave marker, which gives his birth date as the first of June, so I will take this date as definitive.)

Clausewitz is remembered as the philosopher of war, and I have many times said that the philosophy of war and the philosophy of history are close cousins. If we hold that war is the motor that drives history forward, which many philosophers have argued, then was is the causal mechanism by which history is realized. Hegel and Marx in particular are associated with this view. We could even say that war is the reality of which history is the appearance.

And Clausewitz knew war. It was during the Napoleonic Wars that Clausewitz experienced his baptism by fire, so that his book On War is an account of war during the Napoleonic wars, and it is from On War that a mature conception of war has evolved and continues to evolve. By a “mature conception” I mean a theoretically mature conception of war. Since war inflames passions and feeds off irrationality, it can be difficult to engage with the topic of war with the requisite scientific disinterestedness. Clausewitz was the first to bring the attitude to the Enlightenment to war, and to seek to understand war as a rational process. One could argue that Hegel was doing something like this from a philosophical perspective at about the same time, but Clausewitz was a soldier with intellectual interests, while Hegel was a philosopher with an interest in history. The results were bound to be very different, and they were.

Also, Clausewitz’s understanding of Enlightenment rationalism took place when the romantic reaction against Enlightenment rationalism was already well underway, so, again Clausewitzs rationalism was bound to differ from the high Enlightenment representatives like Gibbon, Hume, and Condorcet. It might even be argued that the changes to Enlightenment rationalism that followed from the romantic reaction facilitated the very possibility of applying scientific reason to an object of knowledge as apparently irrational as war. There is an excellent book about post-Enlightenment science, The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science by Richard Holmes, that tells the story of the development of science during the romantic era. Holmes doesn’t discuss Clausewitz, but it would have fit nicely into the narrative.

As the scientific revolution continued to unfold, new influences came to bear upon the development of science, and this in turn opened up scientific knowledge to further frontiers. Clausewitz reflects both Enlightenment and romantic epistemic imperatives. We can find in Clausewitz an intimation of the distinction between nomothetic and idiographic science:

“One may laugh at these reflections and consider them utopian dreams, but one would do so at the expense of philosophic truth. Philosophy teaches us to recognize the relations that essential elements bear to one another, and it would indeed be rash from this to deduce universal laws governing every single case, regardless of all haphazard influences. Those people, however, who ‘never rise above anecdote’ as a great writer said, and who would construct all history of individual cases-starting always with the most striking feature, the high point of the event, and digging only as deep as suits them, never get down to the general factors that govern the matter. Consequently their findings will never be valid for more than a single case; indeed they will consider a philosophy that encompasses the general run of cases as a mere dream.” (On War, Book Six, p. 374)

This is still true today for those who insist that history is exclusively idiographic. In another work, The Campaign of 1812 in Russia (1823–1825), Clausewitz gave an account of history that seems highly idiographic, but which does not necessarily exclude the possibility of assimilating events to a nomothetic explanation:

“Although we are not inclined to see the events of this world as resulting from individual causes but always take them as the complex product of many forces, so that the loss of a single component can never produce a complete reversal {but only a partial transformation relative to the significance of the component}, we must nevertheless recognize that great results have often arisen from seemingly small events, and that an isolated cause, strongly exposed to the workings of chance, often brings forth universal effects.” (Chapter V, From The Campaign of 1812 in Russia (1823–1825))

Clausewitz had enough of the Enlightenment in him that he looked for the relations that essential elements bear to one another in war, and he was enough of a romantic that he recognized that it would be rash to deduce universal laws governing every single case. So should the study of war be idiographic or nomothetic? As I read Clausewitz, it’s a little of both, and it needs to be a little of both. As our theoretical framework for understanding war increases in sophistication and detail, we might be able to assimilate more individual cases to universal laws, but we won’t exhaust individual cases any time soon.

In an introductory essay to the English translation of On War by Peter Paret we find this description of Clausewitz’s intellectual independence, which was probably a necessary condition for this project:

“…important for our purpose is the intellectual independence with which he approached the fundamental military issues of the age, as well as his sympathy with the aims of humanistic education, and his conviction that the study of history must be at the center of any advanced study of war.” (p. 8)

Clausewitz himself makes the importance of history explicit:

“While there may be no system, and no mechanical way of recognizing the truth, truth does exist. To recognize it one generally needs seasoned judgment and an instinct born of long experience. While history may yield no formula, it does provide an exercise for judgment here as everywhere else.”

Clausewitz is here making a logical point that would later, in the twentieth century, be recognized as the decision problem. A whole series of metalogical theorems on decidability have been proved for various calculi. The problem is to determine a yes or no answer to a question about a theorem, for example, whether or not a given proposition is a theorem of a given system. History is of course much too complex to be reduced to any calculus, so no currently conceivable decision procedure is out of reach for history.

Even if history provides us with no formulae, it still can be a source of insight and judgment. Clausewitz elsewhere in On War goes even further and seems to deny that systemic study could be effective:

“History provides the strongest proof of the importance of moral factors and their often incredible effect: this is the noblest and most solid nourishment that the mind of a general may draw from a study of the past. Parenthetically, it should be noted that the seeds of wisdom that are to bear fruit in the intellect are sown less by critical studies and learned monographs than by insights, broad impressions, and flashes of intuition.” (On War)

Given the state of our knowledge of history, Clausewitz is probably right about this, and we have to mostly depend on insight, impressions, and intuition. However, I would argue that Clausewitz leaves this problem open-ended, especially in light of the earlier quote in which he mentions rising above anecdotes, as insights, impressions, and intuitions without even the possibility of assimilating these to general laws would amount to little more than anecdote, which Clausewitz explicitly says we must rise above.

There is another sense in which we can say that history informs our theoretical conceptions. Raymond Aron wrote a study of Clausewitz, Clausewitz: Philosopher of War, in which he makes an interesting observation:

“In his youth, he introduced moral forces into his theory; in his maturity, he introduced the conceptual distinction needed to reconcile the transhistoric theory with history, in other words the two extreme forms of war, each one conditioned or determined by circumstances or political intentions. In order to establish the equality of status in the two types of war, he had to recognize the unreality of absolute war which in many texts he represented as the only one consistent with the concept.”

Aron is suggesting that Clausewitz’s chief theoretical conception, absolute war, was unreal, but that it is conditioned and determined by historical circumstances. For Aron, history was the force that made theory responsive to practice. This is not all that different from the saying attributed to Thucydides, viz. that history is philosophy teaching by example. Thucydides also said that war is a stern master, and it brings men down to the level of their circumstances. Clausewitz knew this first hand, and when the lessons that philosophy teaches are the lessons of men being humbled despite the pretences to some higher position in the world, then we have been well and truly humbled.

We could call Thucydides’ observation about war being a stern master the Copernican principle of war, because it forces all participants into a recognition of their smallness within and peripherality to the bigger picture. Clausewitz himself had his share of Thucydides’ Copernican principle of war. He was in the thick of things during the Napoleonic wars, serving as aide-de-camp to Prince Augustus Ferdinand of Prussia at the Battle of Jena-Auerstadt on 14 October 1806, where Hegel had glimpsed Napoleon and called him the world-spirit on horseback. Hegel fled Jena carrying the manuscript of his Phenomenology of Mind. Clausewitz was taken prisoner of war along with 25,000 others and spent two years as a prisoner of war in France after the catastrophic defeat of the Prussians at Jena. So Clausewitz experienced war as a stern master and he knew the bitterness of total defeat.

Fichte had also felt the weight of the German defeat by the French. In my episode on Fichte I talked about how he had given a series of public lectures subsequently published as Addresses to a German Nation. When Fichte was delivering this talk he is quoted as having said:

“I know very well what I risk; I know that a bullet may kill me, like Palm; but it is not this that I fear, and for my cause I would gladly die.”

War was also a stern master to Fichte; even those who were not soldiers like Clausewitz risked all. Like Fichte, Clausewitz believed that his people could rally, overcome defeat, and eventually regain their political autonomy. Machiavelli, too, had known defeat and had seen his people humiliated by an occupying force, which was also the French, but several hundred years earlier. Fichte wrote an essay about Machiavelli, which, after Clausewitz read it, he sent a letter to Fichte about his Machiavelli essay. In Clausewitz’s letter to Fichte he wrote this:

“This true spirit of war seems to me to consist in mobilizing the energies of every soldier to the greatest possible extent and in infusing him with warlike feelings, so that the fire of war spreads to every component of the army instead of leaving numerous dead coals in the mass. To the extent that this depends on the art of war, it is achieved by the manner in which the individual is treated, but even more by the manner in which he is employed. The modern art of war, far from using men like simple machines, should vitalize individual energies as far as the nature of its weapons permits — which, to be sure, establishes a limit, for an essential condition of large forces is to have the kind of organization that permits them to be led by a rational will without excessive friction.” (Letter to Fichte)

For Clausewitz, friction was a technical term. He wrote an entire chapter on friction in On War, saying, among much else:

“Friction is the only concept that more or less corresponds to the factors that distinguish real war from war on paper. The military machine — the army and everything related to it — is basically very simple and therefore seems easy to manage. But we should bear in mind that none of its components is of one piece: each part is composed of individuals, every one of whom retains his potential of friction.” (On War)

Returning to the previous quote, Clausewitz names three conditions of modern war as: 1) mobilizing the energies of individual soldiers, 2) leading them with a rational will, and 3) doing so without excessive friction. We don’t have to strain too much to see these conditions of modern war as conditions of the possibility of mass warfare that was eventually realized as the First World War, which I also call the first planetary-scale industrial war.

Clausewitz, fighting in the Napoleonic wars, was positioned to see the prehistory of industrialized warfare. A hundred years later, the prehistory of industrialized warfare eventually morphed into the history of industrial warfare in the strict sense. In my episode on Ernst Jünger I described industrialized warfare as a boundary condition out of which novel forms of modernity emerge. In particular, mechanized warfare is a boundary condition for an emergent form of heroism distinctive to mechanized warfare. Something qualitatively new had appeared in history, and this novel emergent generated a cluster of other emergents for which mechanized warfare was the boundary condition.

The conditions that Clausewitz described were the boundary conditions for industrialized warfare. Ernst Jünger was positioned to see and describe the emergence of true industrialized warfare, as Clausewitz was positioned to see its prehistory. The two authors testify to distinct periods in the development of planetary-scale industrialized warfare. This is a development that continues today, and continues to generate philosophical commentary on the novel emergents that have appeared in history as a result of industrialized warfare.

Today is not only the birthday of Clausewitz, it is also the 117th anniversary of the birth of Jan Patočka (01 June 1907–13 March 1977), who was born in Turnov, Bohemia, on this date in 1907. Patočka wrote a book on philosophy of history, Heretical Essays in the Philosophy of History, which was influenced by Husserl, Heidegger, and Hannah Arendt, among others. In the Fifth Essay: Is Technological Civilization Decadent, and Why? And especially in the Sixth Essay: Wars of the Twentieth Century and the Twentieth Century as War, Patočka discussed Ernst Jünger. I mentioned in my episode on Jünger that Jünger’s essay on total mobilization and his book The Worker was an influence on Heidegger, and Patočka too is interested in this work. Patočka’s description of the industrialization of Germany gives us the rational will and the organizational expertise to overcome the friction that Clausewitz saw as conditions of modern war:

“…Germany, for all its traditional structures, is the configuration that most closely approximated the reality of the new technoscientific age. Even its conservatism basically served a discipline that, contemptuous of equalization and democratization, vehemently and ruthlessly pursued the accumulation of building, organizing, transforming energy. Ernst Junger’s Der Arbeiter contains an implicit suspicion of the actual revolutionary nature of the old prewar Germany.! It is above all the ever deepening technoscientific aspect of its life. It is the organizing will of its economic leaders, its technocratic representatives forging plans leading inevitably to a conflict with the existing global order.”

Patočka also saw the orgiastic craziness of modern war that facilitated the mobilization of the energy of individual soldiers:

“War as a global ‘anything goes,’ a wild freedom, takes hold of states, becoming ‘total.’ The same hand stages orgies and organizes everydayness. The author of the five-year plans is at the same time the author of orchestrated show trials in a new witch hunt. War is simultaneously the greatest undertaking of industrial civilization, both product and instrument of total mobilization (as Ernst Jünger rightly saw), and a release of orgiastic potentials which could not afford such extreme of intoxication with destruction under any other circumstances. Already at the dawn of modernity, at the time of the wars of religion in the sixteenth. and seventeenth centuries, that kind of cruelty and orgiasm emerged. Already then it was the fruit of a disintegration of traditional discipline and demonization of the opponent though never before did the demonic reach its peak precisely in an age of greatest sobriety and rationality.”

It took the scientific and managerial resources of industrialized civilization — which Patočka and others call “technoscience” — to tame, and direct, and organize the orgiastic fury that was earlier released during the religious wars of the early modern period. I suspect that Junger would have largely agreed with this if he had read Patočka, and he could have read this since he lived longer than Patočka. It’s a bit more difficult to ascertain what Clausewitz would have thought of this.

To a certain extent it’s counter-intuitive to understand this orgiastic fury of warfare that Patočka described as a moral factor of war. We would perhaps like to think of the morality of war in terms of the various treaties like the Geneva Conventions that have attempted to moderate the brutality of armed conflict, or maybe the older framework of St. Augustines conception of a “just war.” There is, however, a wider sense of the use of the word “moral.” This wider sense of moral is less common that in the past. One could even say that this usage is becoming archaic. This is definitely is case with the idea of what were once called the moral sciences.The OED defines the moral sciences as:

(a) Those branches of knowledge which deal with the criteria of right and wrong;

(b) Cambridge University politics, philosophy, and economics, as a course of study.

This is now a defunct and archaic way to refer to the humanities and the social sciences. I suspect few if any university catalogs continue to use the moral sciences as a major division of the curriculum. But the idea of the moral sciences points to a wider sense of the term moral, and that is anything that engages specifically human responses to the world like politics, philosophy, and economics. In this context, moral doesn’t necessarily involve right and wrong, but it does involve what is human, all-too-human.

The Clausewitzean conception of war, which, as Raymond Aron said, was about introducing moral forces into our understanding of war, makes the study of war a moral science in this now archaic usage of “moral.” Clausewitz’s moral science of war is very close to what Ernst Jünger wrote about war being ultimately a spiritual endeavor. Patočka underlines this by recognizing the many social forces that came together to produce the wars of the twentieth century. Earlier I said that many philosophers have understood war as the engine that drives history forward. Patočka comes close to saying as much further along in his discussion of Jünger’s work:

“The first world war is the decisive event in the history of the twentieth century. It determined its entire character. It was this war that demonstrated that the transformation of the world into a laboratory for releasing reserves of energy accumulated over billions of years can be achieved only by means of wars. Thus it represented a definitive breakthrough of the conception of being that was born in the sixteenth century with the rise of mechanical natural science. Now it swept aside all the ‘conventions’ that inhibited this release of energy — a transvaluation of all values under the sign of power.” (Heretical Essays in the Philosophy of History, Sixth Essay, p. 124)

Clausewitz lived before this radical transvaluation of values, which is a phrase that Patočka has picked up from Nietzsche. Clausewitz belonged to the social order that was subsequently lost to the transvaluation of all values under the sign of power. He was there for the first stirrings of this transvaluation, but he did not see the completed arc of its development. Clausewitz’s traditionalism can be glimpsed in a document Clausewitz wrote in 1812 — titled “Political Declaration” and published in Carl Von Clausewitz: Historical and Political Writings. Clausewitz wrote in the present tense, as a participant in historical events whose outcome was unknown as he wrote this account:

“The hatred that Napoleon bears toward the House of Hohenzollern is of course not obvious to everyone and not at all easy to explain. For some, however, it will be enough to know that at Tilsit a contemptuous coldness, indeed a suppressed hatred, could not be missed in the emperor’s personal conduct toward Frederick William III and his family, while the royal family’s conduct toward Napoleon (thanks to a sense of dignity undiminished by politics!) had a more worthy and dignified bearing, which can of course enrage a vain and passionate man even more. There are also specific facts whose significance cannot be mistaken. The basis of Napoleon’s enmity probably lies above all in the liberality that characterizes the Prussian regime, which has attracted attention throughout Germany. Prussia, and particularly her ruling house, has public opinion on her side more than other states, and Napoleon is deeply hostile to this. The south German princes may be weary of French domination, but they have never been independent, they fear the vengeance of outsiders, and are without pride and self-esteem, half admirers and half flatterers of the French emperor. This is not the case with Frederick William III. This king, as everyone knows, is above all an upright man, incapable of hypocrisy: hatred of the French emperor is natural to him, and since he is sensitive and easily offended, his feelings are constantly inflamed by Napoleon’s abuses and can never grow numb. If he has refrained from expressing those feelings for political reasons (great self-possession being natural to him in any case), if he has admirably sacrificed his own dignity and that of his people in this regard, his reticence could never deceive the French emperor, and nothing is more natural than that Napoleon should have seen more deeply into the king’s heart than the king has into his.”

Here Napoleon is the upstart emperor who lacks the depth of dignity that the ancient family of the Hohenzollern possessed. Napoleon knew this, resented it, and the Napoleonic wars were one big cope-and-seethe because of it. The Hohenzollern represent the traditional aristocratic privilege that the French Revolution sought to overturn, and yet Napoleon and the Hohenzollerns found themselves forced into this diplomatic accommodation that both probably found distasteful. Napoleon was drawn into these ancient diplomatic traditions that the Revolution was in the process of sweeping away.

Not only was Napoleon draw into these ancient rituals of diplomacy, in having himself crowned emperor, he was effectively giving new life to these institutions, and the Hohenzollerns were drawn into paying their respects to a representative of the Revolution that would have done with them. For Clausewitz, the Hohenzollerns were an ancient aristocratic family reforming themselves and their kingdom along liberal lines, while Napoleon was the symbol of revolutionary change that threatened the established order of Europe. Patočka understood this, which why, in my earlier quote from him, he discussed the quasi-traditional, but, at the same time, the quasi-revolutionary nature of Imperial Germany, and Jünger’s response to this. This is not something I am prepared to exhaustively sort out, so I will leave it there for the moment.